Would you really expect Sony to admit any fault with their mount though? Not likely. Theoretically they can make just about any lens, but they don't have the same freedom of design. Which we'll see as time goes on. There's a good reason Nikon's mount jumped by nearly 10mm from the DSLR to mirrorless.I love this diagram and explanation, but Sony has stated repeatedly that the mount diameter doesn't limit their lens design. I think they also claimed that the E mount could theoretically take f/0.95 lenses, but that they didn't have any planned. Would an f/0.95 lens also feature huge elements at the front of the lens and smaller ones at the rear, thus changing/throwing off the balance on the body? According to what you've posted, quite possibly.